Process of conversion of hydrocarbons



R. FLEMING.

PROCESS OF CONVERSION OF HYDROCARBONS.

APPLICATION FILED NOV- ll. 1916.

- Patented Dec. 9,1919.

RICHARD FLEMING, OF SWAMPSCOTT, MASSACHUSETTS, ASSIGNOR' TO THE RICHARD FLEMING COMPANY, A CORPORATION OF DELAWARE.

PROCESS OF CONVERSION OF HYDROCARBONS.

To all whom it may concern:

Be it known that I, RICHARD FLEMING, a citizen of the United States, residing at Swampscott, in the county of Essex and State of Massachusetts, have invented certain new and useful Improvements in Processes of Conversion of Hydrocarbons, of which the following is a specification.

This invention relates to a process of converting hydrocarbons of relatively high boiling point into hydrocarbons of lower boiling point, and an especial object of the invention is to obtain a product resembling natural crude oil, and containing valuable lighter constituents similar to those in natural crude oil.

Although many processes have been devised for obtaining a greater yield of the low boiling point products generally known as gasolene, such processes have thus far been found ob ectionable for one or more reasons.

In some, wherein high pressure and temper-' ature are required, it has been found difficult, if not impracticable, to build apparatus capable of safely withstanding the stresses produced. In others, the expense of chemicals required prevents commercial success. In others, the processes are not continuous, and the temperatures produced are such as to require frequent stoppage of the plant for cleaning, or for removing parts. In addition, many processes owing to overheating, produce an excessive amount of permanent gases, such as hydrogen and methane, with or without unsaturated hydrocarbons of the aromatic or other series, which give the product an objectionable odor, leave objectionable residues when attempted to be used in internal combustion engines, and require to be removed by a further and expensive treatment before the product is marketable. \Vhere sulfuric acid is used for removing such compounds, an excess of acid is re-' quired, which increases the expense and gives a relatively inferior product.

Distillation under high pressure has been employed in an efiort to convert hydrocarbons from higher to lower boiling characteristics, and is moderately successful when the material treated is of a sufiiciently high boiling point. With the lower boiling fractions just above the gasolene fraction, these processes are not commerclal, because such fractions require somewhat higher temperature for conversion than higher boiling Specification of Letters Patent.

Patented Dec. 9, 1919.

Application filed November 17,1916. Serial No. 131,822.

fractions, so that a sufficiently high temperature cannot be reachedwithout an excessive pressure. At the high temperatures necessitated by high pressure distillation. the tensile strength of steel is seriously affected. Moreover, such distillation processes under high pressure are not continuous, but require large batteries of stills to be used in rotation, 'so that some can be cleaned while others are in vuse.

The object of this invention is to enable the conversion of higher into lower boiling hydrocarbons to be carried on continuously at approximately constant temperature and moderate pressure, whereby not only will th production of gases and unsaturated compounds be a minimum, but the apparatus will not be subjected to excessive temperature or strains.

According to this invention, I treat a. bath or menstruum, preferably of the heaviest obtainable hydrocarbon, such as heavy fuel oils or other heavy pitchy residues with a lower boiling hydrocarbon under moderate pressure, at a temperature above 350 C. A product is thereby obtained which distils over and closely resembles crude oil. When this distillate is subjected to fractionation it yields as much as 65% gasolene. The lighter boiling hydrocarbon, which I use is preferably a burning oil, having a gravity of about 43 B., or what is known in the trade as water white or kerosene distillate. Such oils boil at between 180 C. and 315 0., approximately, and are at present produced at the refineries largely in excess of the consumption, being either stored, or refined for burning oils, or

burned for fuel, as such oils have not here ing, wherein 1 is a lower drum, and 2 an 100 upper drum connected by vertical tubes 3, which latter, together with as much of the lower and upper drums 1 and 2 as necessary, are heated to maintain the bath at the required temperature. 4 represents a furnace 105 from which the heat passes upwardly around part of the tubes 3 and then around the b-aflie 5 and downwardly and out at the stackfi, thereby causing an upward flow in the left hand tubes and a downward flow in the right 110 hand tubes. The heavy pitchy residue is constantly supplied through pipe 7 so as to maintain the bath of constant density and at the constant level 33, and the lighter boiling distillate is similarly supplied through the perforated pipe 8-8 located below the pipe 7 and the tubes 3 in such quantity as. not to reduce the working temperature. The bottom of the drum 1 is provided with a settling chamber 10 which receives the carbon as it separates by gravity, and from which 1t can be drawn off as desired. This carbon can be washed with solvents and precipitated and then used for the purposes for which ordinary commercial lamp black 15 now employed. 11 is a gage which shows the level of the bath, 12 is a pressure gage; 18 is a vapor chamber above the level 3 3 of the bath, connected by pipe l-it containing reducing valve 15, to the condensing coil 16 contained in a tank 17. The non-condensable gas and condensed vapors are drawn ofi' at 18 and the gas separated from the vapors in the usual manner. The condensed vapors are then ready for ordinary fractionation in a still under atmospheric pressure, having a color andproperties resembling ordinary crude oil and yielding when fractionally distilled, a large proportion of gasolene together with heavier boiling hydrocarbons. The fractions heavier than gasolene are separated in the usual manner and used forthe same purposes as the same fractions derived from the distillation of crude oil are used.

' The pressure is maintained at from 75 to 100 pounds, and continuous circulation is maintained by reason of the continuous feed of the materials at the bottom of the converter. H

When the menstruum has reached the working temperature, a quantity of the distillate is fed therein. The pressure rapidly comes to the normal predetermined pressure and the vapors flow over into the condenser and are condensed, passing ofi through suitable valves into the run-down tanks, the noncondensable gases being led off to gas holders and used for fuel with or without abstraction of lighter vapors, such methods of abstraction being well known in connection with the recovery of gasolene from casinghead gas, which these gases resemble somewhat closely. The process is continuous as long as the distillates are fed to the menstruum and as long as the level of the menstruum is maintained, provided the temperatures are also maintained. The level of the menstruum is maintained by means of a pump connected to the supply of menstruum, the supply beingpreferably provided with a heating coil so as to maintain the contents fluid if necessary.

The circulation in the converter is rapid and is augmented by injecting the distillate below or in advance of the ascending tubes,

so that the globules of vapor ascend through the Whole column of strongly heated menstruum in intimate contact therewith, and

.are rapidly brought to'the desired temperature of conversion. It is essential that the vapors from the distillate remain in intimate contact with the menstruum for a suflicient time to complete the conversion before being released into the condensers. Underthese conditions the yield or percentage of conversion would be a maximum, and this process has the important advantage of enabling these results to be very accurately controlled and to be attained with the greatest facility without danger of overheating.

In one embodiment of the invention, the menstruum is composed of pitchy residue of about 12 to 20 B.. maintain-ed approximately at its boiling temperature under the pressure used (6. g. about 400 0.), and a continuous supply and circulation is maintained under a constant pressure of from 7 5 to 100 pounds per square inch. Water white or kerosene distillate, of about 43 B., or heavier, boiling above 180 C. is continuously supplied through the perforated pipe 8 in quantity just sufiicient to maintain the pressure, and oil distils over having light and heavy fractions, and yielding a large fraction of gasolene, when condensed and fractionally distilled.

is maintained continuously, with a substantially constant bath, temperature, circulation and pressure as long as materlals are supplied. A menstruum of 12 B. to 20 13.,

Free carbon is drawn off at the bottom as formed, and the processis suitable for use with oilsboiling as high as 325 0., and for higher boiling oils it is desirable to use a still heavier menstruum according to the temperature required for conversion.

The supplies of the bath and the lighter boiling distillate can be heated before entering the converter, if desired, or the lighterboiling distillate can be supplied as vapor, but the important feature of this invention resides first, in the rapid superheating of: the lighter oil distillate when it contacts infine streams with the already hot menstruum; and secondly, in-the prolonged intimate contact of this vapor with the mensiderable portion is found after condensation, to be converted to lower boiling characteristics. A low boiling oil is only slightly decomposed at a temperature corresponding to a pressure of 100 lbs. and unless super-. heated to a relatively higher temperature the amount of conversion is negligible.

By using the heavy menstruum, it is possible to attain the conversion temperature required for the lighter boiling fractions which do not contain gasolene, without raising the pressure correspondingly, and hence it is possible with this process to utilize fractions considerably lighter than gas oil, or. even to use gas oil itself, as well as light fuel oils which have not heretofore-been practically converted by distillation processes owing to the excessive pressures required at the necessary conversion temperatures. The menstruum not only has the function of maintaining the conversion temperature independently of pressure, thereby enabling the. pressure to be varied as desired so as to obtain the best results, but enters into the reaction and is itself partly converted, being continually replenished and maintained at constant density and temperature. Apparently, the relatively complex molecules of both the lighter and the heavier boiling hydrocarbons are broken up into the simpler molecules constituting gasolene, etc.

By this process no steam, catalyzers, or desulfurizers are employed. The free carbon formation is very low by reason of the main-- tenance of the temperature of the bath materially below the decomposition temperature at which excess carbon and gas are formed. Owing to the continuous circulation, there is no local overheating of the tubes or other parts ofthe converter, and there is not at any time an exposure of a red hot tube to the vapors, which causes undesired decom position. I have found that moderate pressure tends to reduce the formation of gases, while excess temperature, or local overheat ing, with or without high pressure, tends to produce unsaturated hydrocarbons, excess carbon, and gases.

From distillation at atmospheric pressure of the conversion product obtained from the pitchy residue and a water white distillate of 43 B. gravity, I have obtained 64% of crude gasolene, ready for the usual gasolene purification process. The residue from this is carried back to the converter and used in continuation of the process.

In this process, the temperature employed should not be so high as to cause extended decomposition of the menstruum, but the menstruum itself shouldbe heavy, and be maintained approximately .L at its boiling point under pressure in the converting ap paratus, and entirely independently of the amount of lower boiling distillate supplied thereto. In other words, the lower boiling distillate constitutes a reagent entering actively into the production of the product, and not a solvent or diluent of the menstruum. It is also to be noted that the men-- struum and the lighter distillates employee in this process are both refinery products, so

variety of distillates, and it expresslyis not' limited to any particular menstruum, distillate, pressure or temperature, except as stated in the appended claims.

What I claim is:

1. The process which consists in heating under pressure of approximately 75 lbs. and upward in a closed-vessel a column of heavy liquid hydrocarbon to approximately its boiling point under said pressure, and passing a lower boiling hydrocarbon vapor in prolonged contact through said column of heated heavy hydrocarbon, whereby the resulting vapors are heated above the cracking point under such pressure as to retard the formation of unsaturated hydrocarbons and gases.

2. The process which consists in heating under substantially constant pressure of approximately 75 lbs. and upward in a closed vessel a column of heavy liquid hydrocarbon maintained at substantially constant height to approximately its boiling point under said pressure, and passing a lower boiling hydrocarbon vapor 1n prolonged contact through said column of heated heavy hydrocarbon, whereby the resulting vapors are heated above the cracking point under such pressure as to retard the formation of unsaturated hydrocarbons and gases.

3. The process which consists in passing vapor of a hydrocarbon boiling at or about 180 C. in prolonged contact with a column of liquid hydrocarbon menstruum having a boiling point at or above 350 heated in a closed vessel to approximately said boiling point under a pressure of approximately 75 pounds, and condensing the resulting vapors from the top of said vessel.

4. The process which consists in heating a column of liquid hydrocarbon menstruum having a boiling point at or above-350 C in a closed vessel to approximately said boiling point, passing vapor of a low boiling hydrocarbon in prolonged contact through said column of heated heavy hydrocarbon in such quantity as to produce a pressure of approximately 7 5 pounds in said vessel and condensing the vapors resulting from such temperature and pressure.

5. The process of cracking which consists in vaporizing a hydrocarbon boiling at between 180 C. and 350 0., and passing the resultant vapors at a pressure of between 75 and 100 pounds per square inch through a hydrocarbon heated to 350 C. or upward.

6. The process of cracking which consists in heating a hydrocarbon having a gravity of B. or lighter, to a temperature of 350 C. or over, and passing vapor of a distillate heavier than B. therethrough at a pressure of between and pounds per square inch.

7. The process of producing oil having high and low boiling fractions which consists in treating a liquid hydrocarbon menstruum at or above 350 C. with superheated vapor of a lower boiling hydrocarbon and under a pressure approximating 75 to 100 pounds per square inch.

8. The process which consists in heating a liquid hydrocarbon menstruum to or above 350 in a closed vessel while maintaining a constant level, passing vapor of ahydrocarbon boiling above 180 therethrough in a quantity tending to maintain a pressure of between 75 to 100 pounds per square inch, and collecting and condensing the resulting vapors.

RICHARD FLEMING. 

